This invention relates to storage of nuclear fuel assemblies and more particularly, to the consolidation of the spent nuclear fuel rods and compaction of a nuclear fuel assembly skeleton.
After a period of operation of a nuclear reactor, the fuel assemblies comprising the core of the nuclear reactor must be rearranged with the depleted or spent fuel assemblies being replaced with fresh ones. The spent fuel assemblies are removed from the reactor vessel and generally stored in a pool of water on the reactor site. Since a conventional fuel assembly comprises structure other than fuel rods such as grids and control rod guide tubes, the spent fuel assembly occupies more space in the storage pool than would be required for the individual fuel rods. Because the storage pool has a finite volume, it would be desirable to be able to store the fuel rods in a closely-packed array and with a minimum of support structure to thereby maximize the amount of spent nuclear fuel rods that can be stored in a given volume of the storage pool. This would provide greater storage capacity for the spent fuel rods until the fuel rods are transported off the reactor site for storage or reprocessing.
However, since the spent fuel rods have been irradiated during reactor operation, they are highly radioactive and can be handled only by remote manipulators and while the fuel rods are submerged in a coolant. The radioactive nature of the spent fuel assemblies increases the difficulty of not only transporting the spent fuel assembly but also dismantling the fuel assembly and storing the spent fuel rods.
In copending Patent Application Ser. No. 268,225, filed May 29, 1981, in the name of P. Pomaibo et al., and entitled "Spent Fuel Consolidation System", there is described a system for vertically and remotely dismantling an irradiated nuclear fuel assembly while the fuel assembly remains submerged in a coolant and for consolidating the spent fuel rods of the dismantled fuel assembly. According to Pomaibo et al., the spent nuclear fuel rods are removed from the spent fuel assembly without damaging the fuel rods and the fuel rods are then rearranged into a consolidated configuration. Once the spent fuel rods have been removed from the fuel assembly, the remainder of the fuel assembly which is generally referred to as the spent fuel assembly skeleton may be disposed of separately from the nuclear fuel rods. While Pomaibo et al. describe a system for consolidating the nuclear fuel rods, they do not address the subject of consolidation or compaction of the spent nuclear fuel assembly skeleton.
Therefore, what is needed is a system for compacting the spent nuclear fuel assembly skeleton once the nuclear fuel rods have been removed therefrom.